Neuromodulatory interventions for reducing neuropathic pain after spinal cord injury

The investigational medical device in this clinical trial includes two devices, electroencephalography (EEG) neurofeedback and transcranial direct current stimulation (tDCS), evaluated individually and in combination. Group 1: EEG-NF + active tDCS Group 2: EEG-NF + sham tDCS Group 3: Active tDCS Group 4: Sham tDCS All interventions are home-based and self-administered by participants for 20 sessions over a 5-week period, with one session completed per day. Each session will last approximately 60 min for Groups 1 and 2, and 30 min for Groups 3 and 4. Adherence is assessed through automatic logging of device usage and completion data, which are uploaded in real time to a secure, study-specific dashboard accessible only to the research team. This system allows for continuous monitoring of session completion and engagement across all study arms. Active tDCS will be delivered using the Sooma Duo tDCS device. The device will be pre-programmed to provide active stimulation at 2 mA for the entire treatment session, with a gradual ramp-up to 2 mA at a rate of 0.1 mA/s at the beginning and a ramp-down to 0 mA at the same rate at the end of the tDCS session. Stimulation will be delivered through 5 × 5 cm circular rubber electrodes, prepared by soaking sponge pads in saline and securing them within the electrode perimeter. An impedance threshold of 50 kiloohms must be met for the stimulation to begin. If impedance exceeds this threshold, participants will be instructed to apply additional saline solution beneath the electrodes. Using a customized electrode montage, the anodal electrode will be placed on the vertex of the head and held in place using a 3D printed headset. The cathodal electrode will be positioned on the shoulder and kept in place with a shoulder band. The EEG neurofeedback intervention is based on brain-computer interface (BCI) technology. We will be using an OpenBCI system with 3D printed headset. OpenBCI products are used as open-source tools for BCI systems. This EEG headset will be completed by a customised software and gaming interface in Unity game engine (Unity Technologies, USA). Our game scenario provides neurofeedback in an interactive, goal-directed, virtual gaming environment. The EEG headset records brain activity from C1 and C2 electrode sites (over the sensorimotor cortex), with reference electrode placed on the left ear and ground electrode on the right ear. To set up, participants will insert two pre-soaked sponge electrodes into the C1 and C2 electrode holders, then place the headset on their head. They will then play a game on a Surface Pro tablet, where they will view a gaming object (rocket, jellyfish, bird, or plane) that moves based on changes in EEG rhythms. The EEG-NF protocol aims to suppress theta (4–7 Hz) and high-beta (20–30 Hz) bands, while reinforcing the sensorimotor rhythms (SMR, 10–15 Hz). When participants successfully regulate all three bands in the desired direction, the object of the game will move faster or higher, and the background colour will change to give participants visual feedback. At the end of each round, participants will receive feedback on their progress through points. Each EEG neurofeedback session will consist of 5 rounds of neurofeedback games, each lasting 2.5 minutes, with a 30-second break between rounds.